[Haskell-beginners] Beginners Digest, Vol 110, Issue 20

[Dmitry Mamontov]

Hello,

Maybe, using fmap would be enough?

data Proxy = Proxy String

f :: Maybe Proxy -> Maybe String
f = fmap (\(Proxy a) -> a)


2017-08-25 15:00 GMT+03:00 <beginners-request at haskell.org>:

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>    1.  Maybe a -> Maybe b (PICCA Frederic-Emmanuel)
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> Message: 1
> Date: Fri, 25 Aug 2017 08:05:34 +0000
> From: PICCA Frederic-Emmanuel
>         <frederic-emmanuel.picca at synchrotron-soleil.fr>
> To: "beginners at haskell.org" <beginners at haskell.org>
> Subject: [Haskell-beginners] Maybe a -> Maybe b
> Message-ID:
>         <A2A20EC3B8560D408356CAC2FC148E53BB41B8D4 at SUN-DAG3.
> synchrotron-soleil.fr>
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> Content-Type: text/plain; charset="us-ascii"
>
> Hello, I have this
>
> data Proxy = Proxy String
>
> And I want to write a function
>
> f :: Maybe Proxy -> Maybe String
> f ma = case ma of
>            (Just (Proxy a)) -> Just a
>            Nothing -> Nothing
>
> I was wondering if there is no simpler way to do this ?
>
> thanks
>
> Frederic
>
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> End of Beginners Digest, Vol 110, Issue 20
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